1. Field of the Invention
The present invention relates to a CCD (Charge Coupled Device) type solid state image pickup device and more particularly to its structure.
2. Related Background Art
Hitherto, there are a progressive CCD-type solid state image pickup device and an interlace CCD-type solid state image pickup device as typical CCD-type solid state image pickup devices. According to the progressive CCD, data can be read from all of unit pixels arranged in an image region. The progressive CCD has an advantage that the resolution in the vertical direction of the image region is higher than that of the interlace CCD. In the progressive CCD, however, at least three, more generally, four transfer electrodes for transferring charges have to be provided with respect to one pixel.
From the viewpoint of the device structure, it is preferable for both of the progressive CCD and the interlace CCD that the surface of the device is flat. That is, if the surface is not so flat, the accuracy at the time of fabrication deteriorates. For example, when the surface is not so flat, it is necessary to form a thick photo resist film in a photo resist process and a focus margin is reduced. Consequently, it is difficult to proceed a fine pattern. When the fine process is difficult, the degree of integration is lowered and it is difficult to widen the opening of a photoelectric transforming part. That is, when the surface is not so flat, deterioration in the degree of integration and the sensitivity is caused.
It is, therefore, an object of the invention to provide a CCD-type solid state image pickup device having the construction with improved flatness.
It is another object of the invention to provide a CCD-type solid state image pickup device having the construction suited for a fine process.
It is further another object of the invention to provide a CCD-type solid state image pickup device having a wide opening of a photoelectric transforming part.
According to the invention, there is provided a CCD-type solid state image pickup device having a plurality of photoelectric transforming regions in each of which a plurality of photosensitive devices are arranged in a first predetermined direction at predetermined intervals and a plurality of charge transfer regions for transferring charges obtained by photoelectric transforming operation of the photosensitive devices. The photoelectric transforming regions and the charge transfer regions are alternately arranged in a second predetermined direction which perpendicularly crosses the first predetermined direction. The device also has bridge regions provided at the predetermined intervals of the photoelectric transforming regions in order to connect the charge transfer regions neighboring in the second predetermined direction. The bridge region has a first wiring extending in the second predetermined direction, an insulating film formed so as to cover the periphery of the first wiring in the bridge region, and second and third wirings formed via the insulating film on the side wall part of the first wiring in the first predetermined direction so as to extend in the second predetermined direction.
According to the invention, since it is constructed so that another wiring is arranged on the side wall part of one wiring, the flatness is improved. Consequently, when a resist is applied on the whole face, a thin photo resist can be used. The focus margin is accordingly enlarged and a process of a fine pattern is facilitated. Since etching residue does not easily occur on the side wall part of the base pattern in the event of etching a shielding film, the yield is improved.